Re: 120 dual master cylinder

Posted by Ross On 2017/12/26 21:27:24

Yes, when one half of dual system develops a leak, one or the other of the two pistons within the cylinder must go to the very end of its travel before pressure is developed behind the other piston. If, say, tubing at the rear of the car fails: The front piston must move all the way to the end of the bore and stop before the piston behind it begins to create some pressure for the front brakes. If the front brakes with their relatively large cylinders are somewhat out of adjustment, you will need a looong push before pressure is built up. In a factory system that is taken into account as well as possible, but if not properly designed the pedal will be to the floor before that rear piston has brought the shoes out to the drums. In which case the dual cylinder was a fool's paradise.

More simply stated, the stroke of the pushrod must be sufficient to bottom both pistons.